P051FPCV Filter Restriction
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- The crankcase ventilation has an oil mist separator or filter element that can clog; the crankcase pressure sensor then sees rising pressure at a given flow. P051F reports this restriction. No manufacturer document available to us uses it – Ford reports high pressure under P051B. BMW and GM bulletins describe the consequences of a blocked separator: oil pushed past seals, oil mist in the intake and charge air cooler, higher oil consumption. CARB requires the PCV system to be monitored.
- What you may notice
- Check engine light on
- Oil leaks at seals or dipstick
- Oil mist in the intake, higher oil consumption
- Likely causes
- LikelySeparator or filter clogged with oil, soot or sludge
- PossibleIcing in the separator or hose on short winter trips
- PossibleOil change intervals exceeded (sludge)
- RarePressure sensor reading wrong
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €30 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.